A theoretical assessment of oxygen delivery agents and the efficacy of loading and unloading oxygen is described from the standpoint of the partial pressures of oxygen in the lungs, blood, and tissues by Van Liew, et al., J. Appl. Physiol., 81(1):500–508 (1996), and Burkard et al, J. Appl. Physiol., 77(6):2874–2878 (1994). Liquid perfluorocarbons, such as perfluorooctylbromide, perfluorodecalin, perfluorotripropylamine and perfluorotributylamine, have been investigated as oxygen-transporting blood substitutes by, for example, Lowe, Comp. Biochem. Physiol., 87A:825–838 (1987). However, these liquid perfluorocarbons boil at temperatures far above physiological conditions, and thus have a limited ability to thermally expand. This limitation imposes a practical constraint on the amount of infused liquid perfluorocarbon that may be administered to a patient in need of an oxygen-carrying blood substitute. Toxicity problems associated with liquid perfluorocarbon emulsions have also imposed significant limitations on their use, as described, for example, by Jing and Cooper, Biomat. Art. Cells Art. Org., 18:107–117 (1990).
There is a need for oxygen delivery agents or blood substitutes that overcome the problems associated with the prior art. The present invention is directed to these, as well as other, important ends.